Once you get the result from XPath, you use matchList selectors to select specific elements in the query result. The matchList selectors don't use XPath syntax but rather a custom Amazon syntax to target the right elements. The purpose of the matchList selector is to correlate an element in your feed with the Fire App Builder content model so that the right item can be displayed in the Fire App Builder UI.

The examples on this page demonstrate a variety of both XPath queries and matchList selectors. In each example, first a query is used to target specific elements from your feed. Then a matchList parameter is used to select the elements from the query's returns.

With the matchList parameter, there's not an evaluator (as there is with XPath) where you can plug in the syntax and see the result. The only way is to look at how your app builds in Android Studio.